diff --git a/src/testdir/check.vim b/src/testdir/check.vim
index 0bbe7ca..d01dd81 100644
--- a/src/testdir/check.vim
+++ b/src/testdir/check.vim
@@ -17,6 +17,9 @@
 " Command to check for the presence of a working option.
 command -nargs=1 CheckOption call CheckOption(<f-args>)
 func CheckOption(name)
+  if !exists('&' .. a:name)
+    throw 'Checking for non-existent option ' .. a:name
+  endif
   if !exists('+' .. a:name)
     throw 'Skipped: ' .. a:name .. ' option not supported'
   endif